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// Copyright 2008, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// See net/disk_cache/disk_cache.h for the public interface.
#ifndef NET_DISK_CACHE_RANKINGS_H__
#define NET_DISK_CACHE_RANKINGS_H__
#include <list>
#include "net/disk_cache/addr.h"
#include "net/disk_cache/mapped_file.h"
#include "net/disk_cache/storage_block.h"
namespace disk_cache {
class BackendImpl;
// Type of crashes generated for the unit tests.
enum RankCrashes {
NO_CRASH = 0,
INSERT_EMPTY_1,
INSERT_EMPTY_2,
INSERT_EMPTY_3,
INSERT_ONE_1,
INSERT_ONE_2,
INSERT_ONE_3,
INSERT_LOAD_1,
INSERT_LOAD_2,
REMOVE_ONE_1,
REMOVE_ONE_2,
REMOVE_ONE_3,
REMOVE_ONE_4,
REMOVE_HEAD_1,
REMOVE_HEAD_2,
REMOVE_HEAD_3,
REMOVE_HEAD_4,
REMOVE_TAIL_1,
REMOVE_TAIL_2,
REMOVE_TAIL_3,
REMOVE_LOAD_1,
REMOVE_LOAD_2,
REMOVE_LOAD_3,
MAX_CRASH
};
// This class handles the ranking information for the cache.
class Rankings {
public:
// This class provides a specialized version of scoped_ptr, that calls
// Rankings whenever a CacheRankingsBlock is deleted, to keep track of cache
// iterators that may go stale.
class ScopedRankingsBlock : public scoped_ptr<CacheRankingsBlock> {
public:
explicit ScopedRankingsBlock(Rankings* rankings) : rankings_(rankings) {}
ScopedRankingsBlock(Rankings* rankings, CacheRankingsBlock* node)
: scoped_ptr<CacheRankingsBlock>(node), rankings_(rankings) {}
~ScopedRankingsBlock() {
rankings_->FreeRankingsBlock(get());
}
// scoped_ptr::reset will delete the object.
void reset(CacheRankingsBlock* p = NULL) {
if (p != get())
rankings_->FreeRankingsBlock(get());
scoped_ptr<CacheRankingsBlock>::reset(p);
}
private:
Rankings* rankings_;
DISALLOW_EVIL_CONSTRUCTORS(ScopedRankingsBlock);
};
Rankings()
: init_(false), head_(0), tail_(0) {}
~Rankings() {}
bool Init(BackendImpl* backend);
// Restores original state, leaving the object ready for initialization.
void Reset();
// Inserts a given entry at the head of the queue.
void Insert(CacheRankingsBlock* node, bool modified);
// Removes a given entry from the LRU list.
void Remove(CacheRankingsBlock* node);
// Moves a given entry to the head.
void UpdateRank(CacheRankingsBlock* node, bool modified);
// Iterates through the list.
CacheRankingsBlock* GetNext(CacheRankingsBlock* node);
CacheRankingsBlock* GetPrev(CacheRankingsBlock* node);
void FreeRankingsBlock(CacheRankingsBlock* node);
// Peforms a simple self-check of the list, and returns the number of items
// or an error code (negative value).
int SelfCheck();
// Returns false if the entry is clearly invalid. from_list is true if the
// node comes from the LRU list.
bool SanityCheck(CacheRankingsBlock* node, bool from_list);
private:
typedef std::pair<CacheAddr, CacheRankingsBlock*> IteratorPair;
typedef std::list<IteratorPair> IteratorList;
Addr ReadHead();
Addr ReadTail();
void WriteHead();
void WriteTail();
// Gets the rankings information for a given rankings node.
bool GetRanking(CacheRankingsBlock* rankings);
// Finishes a list modification after a crash.
void CompleteTransaction();
void FinishInsert(CacheRankingsBlock* rankings);
void RevertRemove(CacheRankingsBlock* rankings);
// Returns false if this entry will not be recognized as dirty (called during
// selfcheck).
bool CheckEntry(CacheRankingsBlock* rankings);
// Returns false if node is not properly linked.
bool CheckLinks(CacheRankingsBlock* node, CacheRankingsBlock* prev,
CacheRankingsBlock* next);
// Checks the links between two consecutive nodes.
bool CheckSingleLink(CacheRankingsBlock* prev, CacheRankingsBlock* next);
// Controls tracking of nodes used for enumerations.
void TrackRankingsBlock(CacheRankingsBlock* node, bool start_tracking);
// Updates the iterators whenever node is being changed.
void UpdateIterators(CacheRankingsBlock* node);
bool init_;
Addr head_;
Addr tail_;
BlockFileHeader* header_; // Header of the block-file used to store rankings.
BackendImpl* backend_;
IteratorList iterators_;
DISALLOW_EVIL_CONSTRUCTORS(Rankings);
};
} // namespace disk_cache
#endif // NET_DISK_CACHE_RANKINGS_H__
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